Emission control devices are used in the automotive industry for limiting the amount of emissions discharged by the automobile, and to monitor and run diagnostics on the emission control devices. Emission control devices can utilize an electric air pump or a secondary air charger, which inject air into an engine's exhaust system to reduce emissions. It is important to have some way to test the functioning of such a system to ensure the emission reduction is in compliance with the regulations.
In order to monitor or run diagnostics on the emission control device utilizing the electric air pump, the air pump has to be turned on under predetermined conditions. When the air pump is turned on, the engine's oxygen sensors should detect the increase in oxygen in the engine. However, the oxygen sensors may not be able to detect the minimal increase in oxygen in the system, and thus an inaccurate result can be obtained. Further, it may be required to turn the air pump on at a time when the air pump would not normally be turned on or when it is an undesirable time to run the air pump. Under these conditions it is likely that an inaccurate result will be obtained due to operating conditions not being ideal for operating the air pump. In addition, the system will not be as efficient when the air pump must be turned on when it is otherwise desirable to be turned off. This also is undesirable since it draws power and causes wear on the air pump components.
When the emissions control device utilizes the secondary air charger, an air charger system can be diagnosed or monitored using sensors or control units that are only used for running diagnostics on the device. It is, however, undesirable to include sensors or control units in the air charger system that are only used for diagnosing the air charger system. The diagnostic system that only has these single use sensors or control units adds components and thus cost to the air charger system.
Therefore, it is desirable to develop a method for monitoring and diagnosing the air charger system that uses sensors and/or known conditions that are otherwise in the air charger system.